Preheat oven to 375ºF.

In medium bowl, combine flour, cream of tartar, baking soda and 1/4 teaspoon salt; set aside. In large bowl, beat butter and 1-1/2 cups sugar with electric mixer on medium speed until light and fluffy. Add eggs and 1 tablespoon RumChata, mix well. Add flour mixture to the butter mixture; mix only until incorporated.

Roll dough into 1-in. balls. In small bowl, combine remaining 1/4 cup sugar and cinnamon; roll balls in mixture to coat and place 2 in. apart on cookie sheet.

Bake 8-10 minutes or until lightly browned, but still soft. Cool 3 minutes on pan. Remove to cooling grid; cool completely.

For filling, beat shortening, confectioners’ sugar, 1/4 cup RumChata and 1/4 teaspoon salt with electric mixer on medium speed until smooth. Spread cookies with filling and sandwich together. If desired, roll edges of cookies in White Pearlized Sugar.